You CAN switch from your BB to another phone and use data without being charged as long as your APN settings are configured properly. Most smartphones allow you to change the APN settings, many "dumbphones" do not. I currently use a 8310 and previously used a 8100. Between the 8100 and the 8310, I used a MDA (winmo) for a while. I left the BB data on my plan and configured the phone to use the wap.voicestream.com APN, never got charged anything extra. My girlfriend has now switched from her 8100 to the MDA (she doesn't know how to care for a phone and destroyed the 8100) and isn't being charged any extra either.